Pentair MasterTemp 125
A compact, light heater for spas and above-ground pools, best for owners with Pentair automation.
Amazon $2,098$2,098
2.6/5
An affordable heater for above-ground pools and spas where a short warranty and outdoor only installation are acceptable.
- 135,000 BTU/hHeating input
- 82%Efficiency
- Natural gas or propaneGas type
- 1 yearWarranty
Check price at Amazon$2,399
Price checked October 31, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Cupro-nickel heat exchanger tolerates salt pools and unbalanced water
- Light 100 lb cabinet is easy to set on an above-ground pool pad
- Low NOx certified for strict air districts
Cons
- Outdoor only, so it cannot go in a pool house or garage
- Only a 1 year parts warranty with no labor when bought online
- Small input heats a large pool slowly
The Hayward H-Series family
Every Hayward H-Series model we rank, smallest first. Ratings compare each against its own size.
| Model | Heating input | Rating | Price |
|---|---|---|---|
| Hayward H-Series H135FD (this one) | 135,000 BTU/h | 2.6/5 | $2,399 |
| Hayward H-Series H150FD | 150,000 BTU/h | 2.6/5 | $2,999 |
| Hayward H-Series H200FD | 199,900 BTU/h | 3.2/5 | $3,699 |
| Hayward H-Series H250FD | 250,000 BTU/h | 2.3/5 | $3,999 |
| Hayward H-Series H400FD | 399,900 BTU/h | 3.5/5 | $5,099 |
How it scores
The rating comes from 4 measured or published factors, each scored 0-100 against fixed reference points for its size. How we rank explains each one.
Specifications
| Model number | W3H135FDP |
|---|---|
| Heating | |
| Gas input | 135,000 BTU/h |
| Gas type | Natural gas or propane |
| Thermal efficiency | 82% |
| Condensing | No |
| Low NOx | Yes |
| Heat exchanger | Cupro-nickel |
| Max water flow | 125 GPM |
| Installation and controls | |
| Ignition | Electronic |
| Venting | Outdoor |
| Digital controls | Yes |
| Automation or app | Yes |
| Weight | 100 lb |
| Warranty | 1 year |
Alternatives in this size
Hayward H-Series H150FD
A low NOx, salt tolerant spa or small pool heater for owners who buy online and can live with a short warranty.
Amazon $2,999$2,999
$2,119
Compare
Compare the Hayward H-Series H135FD with any other gas pool heater →
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